1. Field of the Invention
The present invention pertains to a battery assembly and in particular to a battery assembly in an uninterruptible power supply (UPS) system that protects users from hazardous voltages.
2. Background of the Invention
Users of uninterruptible power supply (UPS) system having battery pack may be subjected to hazardous voltages when users themselves connect or disconnect the battery from the UPS while the UPS is still active. For instance, certain UPS system designs do not use an isolating transformer to isolate high input AC voltage from the UPS circuit. Therefore, a failure of one or more components of the UPS may result in a hazardous condition where high AC voltage is present at the battery leads. Any exposed battery leads or terminals is may expose the user to this dangerous voltage. Furthermore, under various safety standards in various countries, battery connections need to provide protection that meet certain standards such as the Underwriters Laboratories (UL) finger test and the Verband Deutscher Elektringenieure (VDE) probe test. The UL finger test mandates that a human finger should not come in contact with any live parts during normal operation of a device. The VDE probe test requires a specified probe should not be able to touch the active contacts of the battery or its connectors.
Typically, the battery used in the UPS system are generally cells that have metal electrodes and electrolytic liquid, typically sulfuric acid. During battery operation, the electrolysis of water produces Hydrogen and Oxygen gases, which accumulate within the battery. These gases are typically vented through a vent cap that is provided at the battery. Otherwise, accumulation of these gases creates a highly volatile situation and a spark or flame could ignite these gases creating an explosion that can cause serious damage to the UPS system and/or cause injury to a user of the UPS.
Accordingly, it is desired to provide a method and apparatus that resolves these and other shortcomings of UPS systems that use battery packs.